Enrichment device for fuel injection system



Nov. 18, 1958 H. E. J. PRINGHAM 2,559,617

ENRICHMENT DEVICE FOR FUEL. INJECTION SYSTEM Filed June 21, 1957INVENTOR.

ATTOPNEX United States PatcntOfifiCc 2,860,617 Patented Nov. 18, 1958ENRICHMENT DEVICE FoR FUEL INJECTION SYSTEM Henry E. J. Pringlram,Grosse Pointe, Mich., assignor to General Motors Corporation, Detroit,Mich., a corporation 'of Delaware Application June 21, 1957, Serial No.667,153

'11 Claims. (Cl. 123-119) is particularly adapted for use with a fuelinjection systern of the type utilizing an atmospheric type nozzle suchas shown in copending application Serial No. 608,893, Dolza, filedSeptember 10, 1956.

In the fuel metering system of the previously noted copendingapplication, fuel enrichment for starting and cold running operation isachieved by the use of a solenoid controlled mechanismwhich operatesdirectly on the fuel metering valve so as to insure an increased fuelflow through the valve when fuel enrichment isnecessary. While such asystem works satisfactorily, it represents a relatively expensive typecontrol mechanism.

In the present device means is provided -wliich is adapted to coact withthe atmospheric nozzles to provide fuel enrichment during cold startingand running. It is the purpose of the present device to take advantageof the manifold vacuum which is available at the atmospheric nozzle toprovide a force whereby fuel enrichment is achieved.

It is a further object of the present invention to utilize a controlmechanism which is adapted to restrictthe flow of atmospheric referenceair to the atmospheric nozzle whereby manifold vacuum is adapted toincrease the fuel flow through said nozzle and further which device isadapted to coact with the idle air system insuch a way as to increasethe manifold vacuum force available to achieve the fuel enrichmentnoted.

The present fuel enrichment device has resulted in a considerablysimplified system in that it is able to more effectively utilizecomponents and conditions already existent in the system to achieveenrichment which was previously obtainable only with the addition ofrelatively costly components.

The details of the present invention as well as other objects andadvantages are set forth in the description which follows.

In the drawing:

Figure 1 is a partially sectioned elevational view of a fuel systemembodying the subject invention; and

Figure 2 is a fragmentary enlargement of Figure 1.

The fuel injection system functions in substantially the same manner asin the aforenoted copending application except as will be specificallydescribed herein. In general, the fuel injection system comprises an airintake casing having air induction passage 12 formed therein. A venturi14 is formed in said induction passage which also includes a throttlevalve 16 disposed posteriorly of said venturi. A fuel metering mechanismis shown generally at 13 and is adapted to supply metered quantities offuel to the individual cylinder fuel supply conduits 21). The quantityof fuel supplied to the fuel conduits is proportional to the mass of airflow through induction passage 12 as described in detail in theafore'noted co pending application.

Each fuel conduit 20 terminates in a nozzle 22 supported upon andpartially projecting within the individual cylinder intake passages 24.Each fuel nozzle 22 includes a fuel inlet passage 26 which terminates ina fuel metering orifice 28. The fuel from metering orifice28 isprojected in a stream across the enlarged chamber 30 where it istargeted through a larger orifice 32. The chamber 30 is adapted tocommunicate with a conduit 34 which communicates at its other end withthe airintake casing 10 to provide reference air to the nozzle 22. Theorifice 32 in the nozzle 22 has no metering effect on the fuel flowthrough the nozzle but does meter the quantity of air which is mixedwith the fuel stream prior to its injection into the intake passage 24.As already noted, under normal operating conditions: the reference airin chamber 30 neutralizes the manifold vacuum force acting on the end ofthe nozzle 22 and thereby stabilizes the metered fuel flow.

It is to be noted that air conduit 34 communicates through passage 36with the air induction passage 12 intermediate the throttle valve 16 andthe venturi 14. In this way all air flowing to the cylinders of theengine passes through the venturi 14 and insures a maximum meteringsignal for the fuel metering control device 18.

To provide idle air bypass flow around throttle 16 a branch passage 40leads from anterior throttle passage 36 and communicates withchamber 42and posterior throttle opening 46. In this way a flow network isprovided which is adapted to bypass air around a closed throttle 16 foridling operation.

A plunger valve mechanism 50 is adapted to be slidably mounted inthe-intakecasing 10 so as to respectively control the air flow throughnozzle reference air passage 36 as well as through the idle air bypassnetwork. Plunger 50 includes a stern 52'having a pair of axially spacedlands 54 and 56 adapted to slidably support the plunger within an intakecasing bore 58. Bore 58 intercepts atmospheric air passage 36 aswell asthe idle air bypass chamber 42 and communicates with opening 46. Thelower end 60 of land 54 is-adapted to coact with the atmosphericreference air passage 36 so as to variably restrictthe quantity of airflow therethrough in accordance with the axial position of said landrelative to bore 58. Similarly land 56 is adapted to variably controlthe quantity of idle air flow bypassed around throttle 16' thoughpassages 36, 40, chamber 42 and opening 46.

Stem 52 of plunger 50 projects through an openingin casing wall 62 andextends within a housing 64 projecting from the casing. A hollow pistonmember 66 is slidably disposed within housing 64 and loosely mountedabout the enlarged end 68 of stem 52 so as to be capable of limitedaxial movement relative to said stem. A spring member 70 is disposedwithin the hollow piston 66 and biases against the enlarged end 68 ofstem 52 urging the latter in a downwardly direction so as to seatagainst the closed end 72 of said piston. Another-spring 74 is disposedin housing 64 and seats against casing wall 62 so as to biasthe piston66 and plunger 52 ina" downwardly or air flow restricting direction.

In order to control the movement of plunger50=in accordance with enginetemperature, a temperature responsive means is provided and inthepresent device consists of a bellows 76 disposed within housing"64 andadapted to engage the bottom of piston 66. Bellows 76 communicatesthrough a capillary tube 78 with a temperature responsive bulb 80suitably disposed within a portion of the engine, such as the cooling orexhaust system, which will accurately reflect the temperature of theengine. The bellows 76, tube 78 and bulb80 are filled with a suitablematerial which will expand on being heated to actuate the plunger 50 aswill be discussed subsequently.

To achieve fuel enrichment when the engine is cold the plunger 50 isadapted to block the flow of air to nozzle 22 and also to block the flowof bypass air around throt tle 16, the latter at least when the engineis being cranked. In this way the manifold vacuum force in the cylinderintake passage 12 posteriorly of throttle 16 is maintained at a veryhigh value since all passages which can bleed atmospheric air to theintake passage posteriorly of throttle 16 are blocked. Further, inasmuchas the atmospheric air cannot reach the atmospheric nozzle 22 throughpassage 36 manifold vacuum increases the pressure differential acting onthe nozzle fuel thereby in creasing the flow of fuel through the nozzleand providing fuel enrichment.

With the engine cold the material within the temperature responsivemechanism 76, 78 and 80 will be unexpanded and spring ,74 will movepiston 66 and through spring 70, plunger 50 so that the latter is in itslowermost position causing lands 54 and 56 respectively to block flowthrough passage 34 and idle air chamber 42. This will be the conditionof the plunger when the engine is being cranked. Upon the enginestarting, assuming the throttle 16 to be closed, the manifold vacuum inpassage 12 posteriorly of the throttle will increase and act on theupper end of plunger land 56 moving the plunger upwardly against theforce of spring 70, which is actually of a lesser rate than spring 74,the latter which retains the piston 66 in its original position.Manifold vacuum during the initial running of the engine in shifting theplunger upwardly will cause land 56 to open the idle air networkpermitting idle air to flow around the closed throttle 16. At the sametime land 54 will be moved upwardly to permit a limited amount of air toflow through passage 34 to nozzle 22 reducing manifold vacuum at thenozzle and thereby leaning out the cold cranking mixture.

With the device as thus far described, it is apparent that upon suddenopening of the throttle 16 for acceleration purposes, the manifoldvacuum adjacent land 56 will decrease and spring 74 will once againcause lands 54 and 56 to block the idle air passages 36, 40, 42 and 46as well as the atmospheric reference air passage 34 to again increasethe fuel air mixture for increased power.

As the engine temperature warms the temperature responsive bulb 80 willcause bellows 76 to expand and move the piston 66 upwardly against theforce of spring 74 and at the same time causing the enlarged end 68 ofplunger stem 52 to be abutted by the piston. Piston 66 thereafter willmove plunger 50 upwardly until such time as the bottom end 60 of land 54permits completely unrestricted fiow of air through passage 34 toatmospheric nozzle 22. At the same time the upper end 82 of land 54 isadapted to approach the shoulder 84 formed by bore 58 and chamber 42 andto thereby restrict the idle air flow around throttle 16. This latterrestriction .of-

idle air flow is consistent with the reduced engine idling speed whichis maintainable with a warm as opposed to a cold engine.

I claim:

1 A charge forming device for an internal combustion engine comprisingan air induction passage, a venturi formed in said induction passage, athrottle valve rotatably mounted in said induction passage posteriorlyof said venturi, a source of fuel under pressure, and conduit means forcommunicating said fuel source with the individual cylinders of theengine, means for metering the quantity of fuel flow through saidconduit means in accordance with the mass of air flow through saidventuri, each of said fuel conduit means terminating in a nozzle forsupplying fuel to each cylinder of the engine, first passage meanscommunicating said nozzle with said induction passage anteriorly of saidthrottle for supplying air to said fuel stream prior to its injectioninto said cylinder, second passage means formed in said casing forbypassing air around said throttle, and valve means for restricting airflow through said first and second passage engine comprising an airinduction passage, a venturiv formed in said induction passage, athrottle valve rotatably mounted in said induction passage posteriorlyof said venturi, a source of fuel under pressure, and conduit means forcommunicating said fuel source with the individual cylinders of theengine, means for metering the quantity of fuel flow through saidconduit means in accordance with the mass of air flow through saidventuri, each of said fuel conduit means terminating in a nozzle forsupplying fuel to each cylinder of the engine, first passage meanscommunicating said nozzle with said induction passage anteriorly of saidthrottle for supplying air to said fuel stream prior to its injectioninto said cylinder to negative the effect of manifold vacuum on nozzlefuel flow, second passage means formed in said casing for bypassing airaround said throttle, and valve means for controlling air flow throughsaid first and second passage means, means normally biasing said valvemeans to block air flow through said first and second passage means,temperature responsive means acting on said valve means to increase airflow through the first passage means as engine temperature increases.

3. A charge forming device for an internal combustion engine comprisingan air induction passage, a venturi formed in said induction passage, athrottle valve rotatably mounted in said induction passage posteriorlyof said venturi, a source of fuel under pressure, and conduit means forcommunicating said fuel source with the individual cylinders of theengine, means for metering the quantity of fuel flow through saidconduit means in accordance with the mass of air flow through saidventuri, each of said fuel conduit means terminating in a nozzle forsupplying fuel to each cylinder of the engine, first passage meanscommunicating said nozzle with said induction passage anteriorly of saidthrottle for supplying air to said fuel stream prior to its injectioninto said cylinder, second passage means formed in said casing forbypassing air around said throttle, and valve means for restricting airflow through said first and second passage means whereby manifold vacuumwill act on said nozzle to increase the flow of fuel therethrough, andmeans responsive to engine temperature and manifold vacuum for actuatingsaid valve means.

4. A charge forming device for an internal combustion engine comprisingan air induction passage, a venturi formed in said induction passage, athrottle valve rotatably mounted in said induction passage posteriorlyof said venturi, a source of fuel under pressure, and conduit means forcommunicating said fuel source with the individual cylinders of theengine, means for metering the quantity of fuel flow through saidconduit means in accordance with the mass of air flow through saidventuri, each of said fuel conduit means terminating in a nozzle forsupplying fuel to each cylinder of the engine, first passage meanscommunicating said nozzle with said induction passage anteriorly of saidthrottle for supplying air to said fuel stream prior to its injectioninto said cylinder to negative the effect of manifold vacuum on nozzlefuel flow, second passage means formed in said casing for bypassing airaround said throttle, and valve means for controlling air flow throughsaid first and second passage means, means normally biasing said valvemeans to block air flow through said first and second passage means,temperature responsive means acting on said valve means to increase airflow through the first passage means as engine temperature increases,and means responsive to manifold-vacuum for actuating said valve meansto increase air flow through said first and second passage meansindependently of said temperature responsive means.

5. A charge forming device for an internal combustion engine comprisingan air induction passage, a venturi formed in said induction passage, athrottle valve rotatably mounted in said induction passage posteriorlyof said venturi, a source of fuel under pressure, and conduit means forcommunicating said fuel source with the individual cylinders of theengine, means for metering the quantity of fuel flow through saidconduit means in accordance with the mass of air flow through saidventuri, each of said fuel conduit means terminating in a nozzle forsupplying fuel to each cylinder of the engine, first passage meanscommunicating said nozzle With said induction passage anteriorly of saidthrottle for supplying air to said fuel stream prior to its injectioninto said cylinder to negative the effect of manifold vacuum on nozzlefuel flow, second passage means formed in said casing for bypassing airaround said throttle, and valve means for controlling air flow throughsaid first and second passage means, means normally biasing said valvemeans to block air flow through said first and second passage means,temperature responsive means acting on said valve means to increase airflow through the first passage means and decrease flow through saidsecond passage means as engine temperature increases.

6. A charge forming device as set forth in claim 1 in which said valvemeans comprises a common bore intersecting said first and second passagemeans, and a valve element slidably disposed in said bore, said elementbeing adapted to coact with said first and second passage means tovariably restrict the flow of air therethrough.

7. A charge forming device as set forth in claim 6 in which said valveelement includes a stem having a pair of axially spaced lands formedthereon, said lands respectively coacting with said first and secondpassage means to control air flow therethrough.

8. A charge forming device as set forth in claim 7 in which one of saidlands is adapted to control the flow of air through both said first andsecond passage means.

9. A charge forming device for an internal combustion engine comprisingan air intake casing, an air induction passage formed in said casing, aventuri formed in said induction passage, a throttle valve rotatablymounted in said induction passage posteriorly of said venturi, a sourceof fuel under pressure, and conduit means for communieating said fuelsource with the individual cylinders of the engine, means for meteringthe quantity of fuel flow through said conduit means in accordance withthe mass of air flow through said venturi, each of said fuel conduitmeans terminating in a nozzle for supplying fuel to each cylinder of theengine, first passage means communicating said nozzle with saidinduction passage anteriorly of said throttle for supplying air to saidfuel stream prior to its injection into said cylinder, second passagemeans formed in said casing for bypassing air around said throttle, acommon bore intersecting said first and second passage means, a valveelement slidably disposed in said bore and comprising a stem, a pair ofaxially spaced lands formed on said stem and respectively coacting withfirst and second passage means to control air flow therethrough, ahousing associated with said casing, said stem extending within saidhousing, a hollow piston slidably disposed within the housing, saidpiston being loosely connected to said stem to permit relative axialmovement therebetween, a first member biasing said piston and stem intoengagement, a second member biasing said piston and stem in a directioncausing said lands to restrict air flow through said first and secondpassage means, and engine temperature responsive means adapted to urgesaid valve stem in a direction at least initially increasing air flowthrough said first and second passage means.

10. A charge forming device as set forth in claim 9 in which said valveelement communicates with said induction passage posteriorly of thethrottle permitting manifold vacuum to move said element independentlyof said temperature responsive means by compressing said first biasingmember.

11. A charge forming device as set forth in claim 9 in which one of saidlands communicates with said induction passage permitting manifoldvacuum to move said one land to increase air flow through said secondpassage means, said temperature responsive means being adapted to movethe other of said lands to increase flow through said first passagemeans and decrease flow through said second passage means as enginetemperature increases.

No references cited.

